High-power white LEDs

ABSTRACT

A light emitting apparatus has a first radiation source without a dome, a substantially transparent and light transmissive optic device devoid of scattering particles and phosphor, a lens, a down conversion material containing phosphor that is disposed on the planar top surface of the optic device between the lens and the radiation source, and a heat sink, upon which the radiation source is mounted, having a recess formed therein in which the radiation source, the optic device and the down conversion material are positioned, wherein an air space is defined between a boundary of the recess and the optic device.

CROSS REFERENCE TO RELATED APPLICATION

This application is a Divisional Application of U.S. patent applicationSer. No. 13/453,301, filed Apr. 23, 2012, now abandoned, which is aContinuation Application of U.S. patent application Ser. No. 12/987,315,filed Jan. 10, 2011, now U.S. Pat. No. 8,164,825, issued Apr. 24, 2012which is a Divisional Application of U.S. patent application Ser. No.11/644,815 filed Dec. 22, 2006, now U.S. Pat. No. 7,889,421, issued Feb.15, 2011 which claims the benefit of priority to U.S. ProvisionalApplication Ser. No. 60/859,633 filed Nov. 17, 2006, the contents ofwhich is incorporated by reference herein.

BACKGROUND OF THE INVENTION

Solid state light emitting devices, including solid state lamps havinglight emitting diodes (LEDs) and resonant cavity LEDs (RCLEDs) areextremely useful, because they potentially offer lower fabrication costsand long term durability benefits over conventional incandescent andfluorescent lamps. Due to their long operation (burn) time and low powerconsumption, solid state light emitting devices frequently provide afunctional cost benefit, even when their initial cost is greater thanthat of conventional lamps. Because large scale semiconductormanufacturing techniques may be used, many solid state lamps may beproduced at extremely low cost.

In addition to applications such as indicator lights on home andconsumer appliances, audio visual equipment, telecommunication devicesand automotive instrument markings, LEDs have found considerableapplication in indoor and outdoor informational displays.

With the development of efficient LEDs that emit short wavelength (e.g.,blue or ultraviolet (UV)) radiation, it has become feasible to produceLEDs that generate white light through down conversion (i.e., phosphorconversion) of a portion of the primary emission of the LED to longerwavelengths. Conversion of primary emissions of the LED to longerwavelengths is commonly referred to as down-conversion of the primaryemission. An unconverted portion of the primary emission combines withthe light of longer wavelength to produce white light.

Phosphor conversion of a portion of the primary emission of the LED isattained by placing a phosphor layer in an epoxy that is used to fillthe reflector cup which houses the LED within the LED lamp. The phosphoris in the form of a powder that is mixed into the epoxy prior to curingthe epoxy. The uncured epoxy slurry containing the phosphor powder isthen deposited onto the LED and subsequently cured.

The phosphor particles within the cured epoxy generally are randomlyoriented and interspersed throughout the epoxy. A portion of the primarylight emitted by the LED passes through the epoxy without impinging onthe phosphor particles, and another portion of the primary radiationemitted by the LED chip impinges on the phosphor particles, causing thephosphor particles to emit longer wavelength radiation. The combinationof the primary short wavelength radiation and the phosphor-emittedradiation produces white light.

Current state of the art phosphor-converted LED (pc-LED) technology isinefficient in the visible spectrum. The light output for a singlepc-white LED is below that of typical household incandescent lamps,which are approximately 10 percent efficient in the visible spectrum. AnLED device having a light output that is comparable to a typicalincandescent lamp's power density necessitates a larger LED chip or adesign having multiple LED chips. Moreover, a form of direct energyabsorbing cooling must be incorporated to handle the temperature rise inthe LED device itself. More particularly, the LED device becomes lessefficient when heated to a temperature greater than 100° C., resultingin a declining return in the visible spectrum. The intrinsic phosphorconversion efficiency, for some phosphors, drops dramatically as thetemperature increases above approximately 90° C. threshold.

A conventional LED chip is encapsulated by an epoxy that may be referredto as a dome or an epoxy dome. Light from the encapsulated LED passesthrough the encapsulating substance of the dome before passing through atransmission medium, such as air. The encapsulating substance of thedome performs at least two functions. First, allows for beam control;i.e., it helps to control the direction of light rays passing from theLED chip to a destination. Second, it increases the efficiency of lighttransmission between the LED and air. The encapsulating substance of thedome performs these two functions at least in part because the value ofthe refractive index of the encapsulating medium is between therefractive index of the LED chip and the refractive index of air. In aconventional LED chip, the height of the dome may be in the range of 2mm to 10 mm.

SUMMARY OF THE INVENTION

An embodiment of this invention is a light emitting apparatus having aradiation source for emitting short wavelength radiation. A downconversion material receives and down converts at least some of theshort wavelength radiation emitted by the radiation source and backtransfers a portion of the received and down converted radiation. Anoptic device adjacent the down conversion material at least partiallysurrounds the radiation source. The optic device is configured toextract at least some of the back transferred radiation. A sealantsubstantially seals a space between the radiation source and the opticdevice.

Another embodiment of the invention is a light emitting apparatus havinga plurality of radiation sources for emitting short wavelengthradiation. A down conversion material receives and down converts atleast some of the short wavelength radiation from at least one of theplurality of radiation sources and back transfers a portion of thereceived and down converted radiation. An optic device adjacent the downconversion material at least partially surrounds the plurality ofradiation sources and is configured to extract at least some of theradiation back transferred from the down conversion material. A sealantsubstantially seals a space between the plurality of radiation sourcesand the optic device.

Still another embodiment of the invention is a light emitting apparatushaving a plurality of radiation sources for emitting short wavelengthradiation. A plurality of down conversion material layers respectivelyreceives and down converts at least some of the short wavelengthradiation emitted by respective ones of the radiation sources and backtransfers respective portions of the respectively received and downconverted radiation. There are a plurality of optic devices. Respectiveoptic devices are adjacent respective down conversion material layers.Respective ones of the optic devices at least partially surroundrespective ones of the radiation sources. Respective optic devices areeach configured to extract at least some of the radiation backtransferred from respective down conversion material layers or radiationfrom respective radiation sources. A plurality of sealants substantiallyseal respective spaces between respective radiation sources andrespective optic devices.

Another embodiment of the invention is a method of manufacturing a lightemitting apparatus. A down conversion material is placed on a firstportion of an optic device that is configured to extract at least one ofradiation back transferred from the down conversion material orradiation emitted from a short wavelength radiation source. An apertureis formed in a second portion of the optic device. A sealant is placedon a surface of the second portion of the optic device. The radiationsource is inserted into the aperture wherein at least one surface of theradiation source contacts the sealant. The optic device is placed on asupport.

Another embodiment of the invention is another method of manufacturing alight emitting apparatus. A down conversion material is placed on afirst portion of an optic device that is configured to extract at leastone of radiation back transferred from the down conversion material orradiation emitted from a short wavelength radiation source. An apertureis formed in a second portion of the optic device. A sealant is placedon a surface of the second portion of the optic device inside theaperture. The radiation source is placed on a support. The optic deviceis placed onto the support and over the radiation source so that theoptic device at least partially surrounds the radiation source.

Yet another embodiment of the invention is a light emitting apparatushaving a radiation source for emitting short wavelength radiation. Adown conversion material receives and down converts at least some of theshort wavelength radiation emitted by the radiation source and backtransfers a portion of the received and down converted radiation. Anoptic device adjacent the down conversion material and the radiationsource is configured to extract from the optic device at least one ofback-transferred radiation or radiation from the radiation source. Afirst reflective surface at least partially surrounds the optic devicefor reflecting at least some of the light extracted from the opticdevice. A second reflective surface at least partially surrounds theradiation source for reflecting at least some of the radiation emittedby the radiation source.

Still another embodiment of the invention is a light emitting apparatushaving a plurality of radiation sources for emitting short wavelengthradiation. A down conversion material receives and down converts atleast some of the short wavelength radiation from at least one of theplurality of radiation sources and back transfers a portion of thereceived and down converted radiation. An optic device adjacent the downconversion material at least partially surrounds the plurality ofradiation sources and is configured to extract at least some of theradiation that is back transferred from the down conversion material. Asealant substantially seals a space between the plurality of radiationsources and the optic device.

Another embodiment of the invention is another method of manufacturing alight emitting apparatus having a first reflective cup and a secondreflective cup. A down conversion material is placed on a first portionof an optic device that is configured to extract one of radiation backtransferred from the down conversion material or radiation emitted froma short wavelength radiation source. A first surface of the radiationsource is placed on a first surface of a well that is formed by thesecond reflective cup. A first sealant is placed between at least asecond surface of the radiation source and a second surface of the well.A second sealant is placed on at least a third surface of the radiationsource. The optic device is placed within the first reflective cup andin contact with the second sealant.

BRIEF DESCRIPTION OF THE DRAWINGS

It will be understood that the figures are not drawn to scale and thatthe relative size of certain features may be exaggerated for ease ofillustration.

FIG. 1 is a diagram illustrating the exemplary radiation rays that mayresult when an exemplary radiation ray from a short-wavelength radiationsource such as an LED chip impinges on a layer of down conversionmaterial;

FIG. 2 is a partial cross-section view of an optic device making use ofa down conversion material that is remote from a short wavelengthradiation source;

FIG. 3 is a partial cross-section view of a light emitting apparatusaccording to an exemplary embodiment of the present invention;

FIG. 4 is a partial cross-section view of the optic device illustratedin FIG. 3 having an exemplary embodiment of an aperture;

FIG. 5 is a partial cross-section view of the optic device illustratedin FIG. 3 having an alternative embodiment of an aperture;

FIG. 6 is a partial cross-section of an embodiment of the inventionhaving an exemplary embodiment of a lens adjacent the down conversionmaterial;

FIG. 7 is a partial cross-section of an alternative embodiment of theinvention that does not have a lens adjacent the down conversionmaterial;

FIG. 8 is a partial cross-section of another alternative embodiment ofthe invention having an alternative embodiment of a lens adjacent thedown conversion material;

FIG. 9 is a partial cross-section of yet another alternative embodimentof the invention having yet another alternative embodiment of a lensadjacent the down conversion material;

FIG. 10 is another embodiment of the invention wherein a plurality ofshort wavelength radiation sources are used;

FIG. 11 is another embodiment of the invention having a plurality ofshort wavelength radiation sources;

FIG. 12 is yet another embodiment of the invention having a plurality ofshort wavelength radiation sources;

FIG. 13 is still another embodiment of the invention having a pluralityof reflective surfaces adjacent the radiation source and the opticdevice;

FIG. 14 illustrates an exemplary embodiment of a method that may be usedto manufacture any of the embodiments of the invention described inconnection with FIGS. 3-12;

FIG. 15 illustrates another embodiment of a method of manufacturing anyof the embodiments of the invention described in connection with FIGS.3-12;

FIG. 16 illustrates an exemplary embodiment of a method that may be usedto manufacture the embodiment of the invention described in connectionwith FIG. 13;

FIG. 17 is a partial cross-section view of an optic device in accordancewith still another embodiment of the invention;

FIG. 18 is another partial cross-section view of the embodimentillustrated in FIG. 17;

FIG. 19 is a partial cross-section view of still another embodiment ofthe invention;

FIG. 20 is another partial cross-section view of the embodimentillustrated in FIG. 19;

FIG. 21 illustrates an exemplary embodiment of a method of manufacturingeither of the embodiments illustrated in FIGS. 17-20; and

FIG. 22 illustrates another embodiment of a method of manufacturingeither of the embodiments illustrated in FIGS. 17-20.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a diagram illustrating the exemplary radiation rays that mayresult when an exemplary radiation ray 2000 from a short-wavelengthradiation source such as an LED chip 2002 impinges on a layer of downconversion material 2004. The impingement of exemplary short-wavelengthradiation 2000 from a short-wavelength source such as an LED chip 2002onto a down conversion material layer 2004 may produce radiation withfour components: back transferred short-wavelength radiation 2006reflected from the down conversion material layer 2004; forwardtransferred short-wavelength radiation 2008 transmitted through the downconversion material layer 2004; forward transferred down-convertedradiation 2010 transmitted through the down conversion material 2004;and back transferred down-converted radiation 2012 reflected from thedown conversion material 2004. The four components may combine toproduce white light.

Two of the four components 2010 and 2012 may each be comprised of twosub-components. One of the sub-components of forward transferreddown-converted radiation may be emitted radiation 2014; i.e.,down-converted radiation having a longer wavelength than theshort-wavelength radiation that impinges onto the down conversionmaterial layer 2004. The emitted radiation sub-component 2014 of forwardtransferred down-converted radiation may be produced by short-wavelengthradiation 2000 impinging on particles of the down conversion material2004 as it is transmitted through the down conversion material 2004. Thesecond sub-component of forward transferred down-converted radiation maybe forward scattered emitted radiation 2016; i.e., other down-convertedradiation having a longer wavelength than the short-wavelength radiation2000 that impinges onto the down conversion material layer 2004. Theforward scattered emitted radiation sub-component 2016 of forwardtransferred down-converted radiation 2010 may be produced byshort-wavelength radiation 2000 impinging on particles of the downconversion material 2004 and that also bounces back and forth on theparticles of the down conversion material 2004 before being transmittedthrough the down conversion material 2004.

One of the sub-components of back transferred down-converted radiation2012 may be emitted radiation 2020; i.e., down-converted radiationhaving a longer wavelength than the short-wavelength radiation 2000 thatimpinges onto the down conversion material layer 2004. The emittedradiation sub-component 2018 of back transferred down-convertedradiation 2012 may be produced by short-wavelength radiation 2000impinging on particles of the down conversion material 2004 as it isreflected from the down conversion material 2004. The secondsub-component of back transferred down-converted radiation 2012 may beback scattered emitted radiation 2020; i.e., other down-convertedradiation having a longer wavelength than the short-wavelength radiation2000 that impinges onto the down conversion material layer 2004. Theback scattered emitted radiation sub-component 2020 of back transferreddown-converted radiation 2012 may be produced by short-wavelengthradiation 2000 impinging on particles of the down conversion material2004 and that also bounces back and forth on the particles of downconversion material 2004 before being reflected from the down conversionmaterial 2004.

White light may be produced by the combinations of the variouscomponents discussed above. In the forward transferred direction (i.e.,for radiation 2008, 2014, 2016, 2010 that is transmitted through thedown conversion material layer), white light may be produced by thecombination of forward transferred short-wavelength radiation 2008 witheither or both of the sub-components 2014, 2016 of the forwardtransferred down-converted radiation 2010. That is, white light may beproduced in the forward transferred direction by the combination offorward transferred short-wavelength light 2008 with transmitted emittedradiation 2014 and/or with transmitted forward scattered emittedradiation 2016.

In the back transferred direction (i.e., for radiation 2006, 2018, 2020,2012 that is reflected from the down conversion material layer), whitelight may be produced by the combination of back transferredshort-wavelength radiation 2006 with either or both of thesub-components 2018, 2020 of the back transferred down-convertedradiation 2012. That is, white light may be produced in the backtransferred direction by the combination of back transferredshort-wavelength light 2006 with reflected emitted radiation 2018 and/orwith reflected back scattered emitted radiation 2020.

The wavelength of the forward transferred short-wavelength radiation2008 may be about the same as the wavelength of the radiation 2000emitted by a radiation source such as an LED chip 2002. The wavelengthof the back transferred short wavelength radiation 2006 may be about thesame as the wavelength of the radiation 2000 emitted by the radiationsource 2002. The wavelength of the forward transferred short-wavelengthradiation 2008 may be about the same as the wavelength of the backtransferred short-wavelength radiation 2006. In an exemplary embodiment,the radiation source 2002 may emit radiation exhibiting a wavelengththat is less than 550 nm, more particularly in a range of about 200 nmto less than 550 nm. Accordingly, the wavelength of the forwardtransferred short-wavelength radiation 2008 and the wavelength of theback transferred short-wavelength radiation 2006 may be less than 550nm, more particularly in a range of about 200 nm to less than 550 nm.

The wavelength of the forward transferred down-converted radiation 2010(including its sub-components 2014, 2016) and the wavelength of the backtransferred down-converted radiation 2012 (including its sub-components2018, 2020) may be any wavelength that is longer that the excitationspectrum of the down conversion material 2004. In an exemplaryembodiment, the excitation spectrum of the down conversion material 2004may be in the range of about 300 nm to about 550 nm. In alternativeembodiments, other down conversion materials may be used that have anexcitation spectrum other than in the range of about 300 nm to about 550nm. The excitation spectrum of the down conversion material 2004 shouldproduce radiation having a wavelength that is longer than the wavelengthof the radiation produced by the short-wavelength emitting radiationsource 2002. In an exemplary embodiment, the down conversion material2004 may produce radiation in the range of from about 490 nm to about750 nm.

The inventors have discovered that the performance of phosphor convertedLEDs is negatively affected when placing the down-conversion phosphorclose to the LED die. Poor performance is mainly due to the fact thatthe phosphor medium surrounding the die behaves like an isotropicemitter, and some portion of the back transferred radiation towards thedie circulates between the phosphor layer, the die, and the reflectorcup. As a result, the back transferred radiation increases the junctiontemperature, thus reducing system efficacy and increasing the yellowingof the encapsulant. All of these factors reduce the light output overtime.

The literature shows that 60 percent of the light impinging on thephosphor layer is back transferred, contributing to the describedeffects (Yamada, et al., 2003). Lab measurements of eight YAG:Cephosphor plates proved that nearly 60% of the radiant energy istransferred back in the direction of the blue LED source. The absolutemagnitude of the radiant energy reflected depends, among other factors,on the density of the phosphor coating.

Such effects are expected to be of a higher magnitude in RCLEDs, becausetheir light output is much more collimated. Consequently, the packagingattempts to capture the transmitted, emitted, and reflected componentsto improve system efficiency. Additionally, the inventors have createdpackaging that allows the phosphor layer to be moved away from the die,preventing radiation feedback into the LED and RCLED. As a result, thepackaging increases the efficiency of the device by allowing more of theradiation reflected off and emitted by the phosphor layer to exit thedevice. At the same time, radiation from the RCLED impinges on thephosphor layer uniformly to obtain a uniform white light source. Inaddition, the life of the LED and RCLED is improved.

In traditional phosphor-converted white LEDs, where the phosphor isplaced adjacent the die, more than 65% of the light generated by thephosphor is back-scattered and lost within the LED package. Based onthese findings, a technique referred to as Scattered Photon Extraction™(SPE™) has been developed. An aspect of the technique has been disclosedin pending International Application No. PCT/US2005/015736 filed on May5, 2005 and published at WO 2005/107420 A2 on Nov. 17, 2005.

To increase the light output from a phosphor-converted white LED(pc-LED) and to achieve higher luminous efficacy, the down-conversionmaterial (e.g., phosphor or quantum dots) is removed to a remotelocation and a properly tailored optic device is placed between the LEDchip and the down-conversion material layer. Then, the back transferredlight can be extracted to increase the overall light output andefficacy. This technique significantly increases the overall lightoutput and luminous efficacy of a pc-white LED by extracting thephosphor emitted and back scattered reflected radiation, and thereflected short-wavelength radiation that otherwise would be lost. Theinvention described in this specification may achieve a 1500-lumenpackage at 150 lm/W, for example, using an LED chip array. In anexemplary embodiment, the LED chip array may be nitride-based. Inalternative embodiment, the LED chip array may be AlInN-based or anyother short wavelength emitter.

FIG. 2 illustrates a device using the SPE™ technique. It illustrates ahigh efficiency light source that may use one or more solid stateemitters and down conversion material. It illustrates an optic devicemaking use of a down conversion material that is remote from a shortwavelength radiation source. The down conversion material may be aphosphor or quantum dots. As shown, device 200 may include a radiationsource 202 for emitting short wavelength radiation. Radiation source 202is separated from phosphor layer 204 by optic device 250 which may bemade of a substantially transparent medium that may be substantiallylight transmissive. The substantially transparent medium may be, forexample, air, glass or acrylic. Optic device 250, as well as all of theembodiments disclosed in the application, may be cylindrical in shape ormay have another curved or linear shape. For purposes of illustration,optic device 250 is shown as having walls 252 and 254, which may besubstantially transparent and substantially light transmissive walls.Phosphor layer 204 may be placed adjacent to or on a portion 206 ofoptic device 250.

Phosphor or quantum dot layer 204 may include additional scatteringparticles (such as micro spheres) to improve mixing light of differentwavelengths. Also, the phosphor or quantum dot layer 204 may be of asingle phosphor (or quantum dot) or multiple phosphors (or quantum dots)to produce different colored down-converted radiation that may be inseveral different spectral regions. Alternatively, a layer withscattering particles only may be placed above, or below, or above andbelow the down conversion material layer 204 to improve color mixing.

The portion 206 of optic device 250 upon which phosphor layer 204 may bedeposited may be an end of optic device 250. Radiation source 202 may belocated at another portion of optic device 250. For example, radiationsource 202 may be located at another end 208 of optic device 250. Opticdevice 250 may be placed upon a base 256.

Short wavelength radiation source 202 may be located between walls 252and 254. Both the short wavelength radiation source 202 and the opticdevice 250 may be positioned on the base 256.

Exemplary radiation rays 214 may comprise radiation transmitted throughphosphor layer 204 including forward transferred short-wavelengthradiation transmitted through the phosphor layer 204 and forwarddown-converted radiation transmitted through the phosphor layer 204.

Exemplary radiation rays 215 may comprise back transferredshort-wavelength radiation and back transferred down-converted reflectedradiation that may be emitted and/or scattered back by phosphor layer204. Exemplary radiation rays 216 may comprise radiation scattered backby phosphor layer 204. Exemplary radiation rays 216 may comprise theradiation rays 215 that may be transmitted through the substantiallytransparent, substantially light transmissive walls 252, 254. Althoughexemplary arrows 215 show back transferred radiation being transferredaround the middle of side walls 252 and 254, it will be understood thatback transferred radiation may be transferred through side walls 252 and254 at multiple locations along the side walls 252 and 254. The transferof radiation outside the optic device 250 may be referred to asextraction of light. Accordingly, both radiation rays 215 and radiationrays 216 may include short wavelength radiation reflected from thephosphor layer 204 and down-converted reflected radiation that may beemitted and/or scattered from the phosphor layer 204. Some or all ofradiation rays 215 and/216 may be seen as visible light.

The transfer (extraction) of radiation through side walls 252 and 254may occur because optic device 250 may be configured and designed withsubstantially transparent, substantially light transmissive walls 252and 254 to extract radiation from inside optic device 250 to outsideoptic device 250. In addition, various widths of optic device 250 may bevaried in order to extract a desired amount of radiation out of theoptic device 250. The widths that may be varied are the width at the end206 and the width at the end 208. Similarly, widths between ends 206 and208 may be varied. The widths between ends 206 and 208 may result inwalls 252 and 254 being substantially straight, curved, or having bothstraight and curved portions.

The dimensions of the features of optic device 250 discussed above maybe varied depending upon the application to which the optic device 250may be used. The dimensions of the features of optic device 250 may bevaried, and set, by using the principles of ray tracing and theprinciples of total internal reflection (TIR). When principles of TIRare applied, reflectivity of radiation off of one or both of walls 252and 254 may exceed 99.9%. The principles of TIR may be applied to all ofthe embodiments disclosed in this application.

The dimensions of optic device 250 may be set in accordance with the useto which the optic device may be put. For example, the dimensions of theoptic device may be set in order to maximize the amount of radiationfrom radiation source 202 that enters into optic device 250.Alternatively, the dimensions of optic device 250 may be set in order tomaximize the amount of radiation from radiation source 202 that impingesupon down conversion material 204. Also alternatively, the dimensions ofoptic device 250 may be set in order to maximize the amount of radiationthat is back transferred from down conversion material 204. Alsoalternatively, the dimensions of optic device 250 may be set in order tomaximize the amount of radiation that is extracted through walls 252 and254. Also alternatively, the dimensions of optic device 250 may be setin order to provide a device that, to the extent possible,simultaneously maximizes each of the radiation features discussed above:the amount of radiation entering into optic device 250; the amount ofradiation that impinges upon down conversion material 204; the amount ofradiation that is back transferred from down conversion material 204;and the amount of radiation that is extracted through walls 252 and 254.In addition, the dimensions of optic device 250 may be set so that anyor all of the features discussed above are not maximized. The principlesof ray tracing and the principles of TIR may be used in order toimplement any of these alternatives.

Some of the dimensions that may be varied are the diameter of end 206 ofthe optic device; the diameter of end 208 of optic device; the angle ofwalls 252 and/or 254 relative to end 208; the shape of walls 252 and/or254. For example, walls 252 and/or 254 may be straight, curved, orcombinations of straight and curved. A height 260 of the optic device250 may be less than 30 mm.

The refractive index of optic device 250 may be in a range from about1.4 to about 1.7. Radiation source 202 may have a refractive index inthe range of about 1.7 to about 2.6. Radiation source 202 may beencapsulated by a material such a radiation transmissive epoxy 220. Theencapsulating material may be referred to as a dome 220. The height ofdome 220 may be about 2 mm to about 10 mm. Dome 220 may be used for beamcontrol and to improve the efficiency of the radiation source, such aswhen the radiation source 202 is an LED. In order to provide theseadvantages, the refractive index of the dome 220 may be in range ofabout 1.4 to about 1.7. The refractive index of dome 220 may be selectedto be between the refractive index of radiation source 202 and therefractive index of optic device 250 so that the dome 220 may provide atransition for radiation between the output of radiation source 202 andoptic device 250.

An aperture is provided in end 208 of optic device 250. The aperture maybe sized and shaped to receive the dome 220 along with the encapsulatedradiation source 202. Accordingly, the height of the aperture may beabout 2 mm to about 15 mm in order to fully receive dome 220.

FIG. 3 is a partial cross-section view of a light emitting apparatusaccording to an exemplary embodiment of the present invention. FIG. 3shows a short wavelength radiation source 302 that may be a lightemitting diode (LED), a laser diode (LD), or a resonant cavity lightemitting diode (RCLED). Radiation emitting source 302 is notencapsulated by a dome. Radiation emitting source 302 may either bemanufactured without a conventional dome or it may be manufactured witha dome, which may be removed as needed. Radiation emitting source 302may emit short wavelength radiation. One side of radiation source 302may be positioned on a heat sink 304 which may transfer heat away fromradiation source 302. An inside surface 306 of heat sink 304 may be areflective surface to form a reflective cup. In an exemplary embodiment,the shape of reflective surface 306 may be a parabola for illustrationpurposes, but it may take any geometric shape such as a concave shape,an elliptical shape, or a flat shape. In an exemplary embodiment, thelength 370 of heat sink 304 may be about 5 mm. Reflective surface 306may direct some of the light extracted from optic device toward downconversion material 310 and may direct some of the extracted lighttoward a lens 340 without impinging upon down conversion material 310.

An optic device 308 may be positioned on the heat sink 304 and over theradiation source 302. Optic device 308 may make use of a down conversionmaterial 310 that is placed on a portion 316 of optic device that isremote from radiation source 302. The down conversion material 310 maybe a phosphor or quantum dots. Radiation source 302 is separated fromphosphor layer 310 by optic device 308 which may be made of asubstantially transparent medium that may be substantially lighttransmissive. The substantially transparent medium may be, for example,air, glass or acrylic. Optic device 308 may have substantiallytransparent and substantially light transmissive walls 312 and 314.

Phosphor or quantum dot layer 310 may include additional scatteringparticles (such as micro spheres) to improve mixing light of differentwavelengths. Also, the phosphor or quantum dot layer 310 may be of asingle phosphor (or quantum dot) or multiple phosphors (or quantum dots)to produce different colored down-converted radiation that may be inseveral different spectral regions. Alternatively, a layer withscattering particles only may be placed above, or below, or above andbelow the down conversion material layer 310 to improve color mixing.

The portion 316 of optic device 308 upon which phosphor layer 310 may bedeposited may be an end of optic device 308. Radiation source 302 may belocated at another portion of optic device 308. For example, radiationsource 302 may be located at another end 318 of optic device 308. Asindicated, optic device 308 may be placed upon a base which may be heatsink 304.

Short wavelength radiation source 302 may be located between walls 312and 314 of optic device 308. Both the short wavelength radiation source302 and the optic device 308 may be positioned on the heat sink 304.

The operation of, and the interrelationship between, radiation source302, optic device 308, and down conversion material 310 may be the sameas the operation and interrelationship between corresponding elementsdescribed and illustrated in FIGS. 1 and 2. Short wavelength radiationemitted by radiation source 302 may result in radiation transmittedthrough phosphor layer 310 including forward transferredshort-wavelength radiation transmitted through the phosphor layer 310and forward down-converted radiation transmitted through the phosphorlayer 310; and back transferred short-wavelength radiation and backtransferred down-converted reflected radiation that may be emittedand/or scattered back by phosphor layer 310. It will be understood thatback transferred radiation may be transferred through side walls 312 and314 at multiple locations along the side walls 312 and 314. The transferof radiation outside the optic device 308 may be referred to asextraction of light. Accordingly, radiation rays that may be extractedfrom optic device 308 may include short wavelength radiation reflectedfrom the phosphor layer 310 and down-converted reflected radiation thatmay be emitted and/or scattered from the phosphor layer 310. Some shortwavelength radiation emitted from the top and the sides of the radiationsource 302 may leave optic device 308 without impinging upon downconversion material 310. Some or all of the extracted short wavelengthreflected radiation and the extracted down converted reflected radiationmay be seen as visible light.

The transfer (extraction) of radiation through side walls 312 and 314may occur because optic device 308 may be configured and designed withsubstantially transparent, substantially light transmissive walls 312and 314 to extract radiation from inside optic device 308 to outsideoptic device 308. In addition, various widths of optic device 308 may bevaried in order to extract a desired amount of radiation out of theoptic device 308. The widths that may be varied are the width at the end316 and the width at the end 318. Similarly, widths between ends 316 and318 may be varied. Variations in the widths of walls 312 and 314 betweenends 316 and 318 may be created by varying shapes of walls 312 and 314.Walls 312 and 314 may be substantially straight, curved, or have bothstraight and curved portions.

The dimensions of the features of optic device 308 discussed above maybe varied depending upon the application to which the optic device 308may be used. The dimensions of the features of optic device 308 may bevaried, and set, by using the principles of ray tracing and theprinciples of total internal reflection (TIR). When principles of TIRare applied, reflectivity of radiation off of one or both of walls 312and 314 may exceed 99.9%. The principles of TIR may be applied to all ofthe embodiments disclosed in this application.

The dimensions of optic device 308 along with characteristics of downconversion material 310 may be set or adjusted in accordance with theuse to which the optic device may be put. For example, the dimensions ofthe optic device may be set in order to maximize the amount of radiationfrom radiation source 302 that enters into optic device 308.Alternatively, the dimensions of optic device 308 may be set in order tomaximize the amount of radiation from radiation source 302 that impingesupon down conversion material 310. Also alternatively, the dimensions ofoptic device 302 may be set in order to maximize the amount of radiationthat is back transferred from down conversion material 310. Alsoalternatively, the dimensions of optic device 308 may be set in order tomaximize the amount of radiation that is extracted through walls 312 and314.

It will also be understood that dimensions of other embodiments of opticdevice 308 and characteristics of down conversion material 310 may beset or adjusted to produce radiation features that are not maximized. Inthese other embodiments, one or more of the amounts of radiationentering into optic device 308; impinging upon down conversion material310; back transferred from down conversion material 310; and extractedthrough walls 312 and 314 may be adjusted to a one or more of a varietyof levels that may be less than their respective maximum levels,depending upon the use to which the optic device is put. The dimensionsof optic device 308 may also be varied depending upon relative costneeds versus the needed efficiency of light extraction for a particularuse of the optic device.

The principles of ray tracing and the principles of TIR may be used inorder to implement any of these alternatives.

Some of the dimensions that may be varied are the diameter of end 316 ofthe optic device; the diameter of end 318 of optic device; the angle ofwalls 312 and/or 314 relative to end 318; the shape of walls 312 and/or314. For example, walls 312 and/or 314 may be straight, curved, orcombinations of straight and curved. In an exemplary embodiment, aheight 360 of the optic device 308 may be about 3 mm.

FIG. 4 is a partial cross-section view of the optic device illustratedin FIG. 3 having an exemplary embodiment of an aperture. Morespecifically, FIG. 4 is a partial cross-section view of optic device 308having an exemplary embodiment of an aperture 320. FIG. 4 shows opticdevice 308 and down conversion material 310 on an end 316 of opticdevice 308. FIG. 4 shows the aperture 320 in end 318 of optic device308. The aperture 320 may be sized and shaped to receive the radiationsource 302 so that optic device 308 at least partially surroundsradiation source 302 because a substantial amount of radiation source302 is within the aperture 320. As shown in the exemplary embodimentillustrated in FIGS. 3 and 4, when radiation source 302 is withinaperture 320, substantially all of the radiation source 302 may besurrounded by optic device 308. The only portion of radiation source 302that may not be surrounded by optic device 308 is the portion that restson heat sink 304. When the radiation source 302 is positioned within theaperture 320 of optic device 308 as shown in FIGS. 3 and 4, it may besaid that radiation source 302 is fully immersed within the optic device308. In an exemplary embodiment, the dimensions of radiation source 302may be about 1 mm by about 1 mm by about 0.3 mm and the diameter ofaperture 320 may be about 2 mm. By using a radiation source without adome, the height 360 of the optic device 308 may be smaller than, forexample, the height 260 of the optic device 250 shown in FIG. 2.

It will be understood that the aperture in the optic device may have avariety of shapes. As shown in FIG. 4, for example, aperture 320 mayhave a curved shape. FIG. 5 is a partial cross-section view of the opticdevice illustrated in FIG. 3 having an alternative embodiment of anaperture. In the alternative embodiment shown in FIG. 5, an aperture 322may be in a shape that more nearly approximates the shape of theradiation source 302. For example, as shown in FIG. 5, the shape ofaperture 322 of optic device 308 may be a trapezoid. In an exemplaryembodiment, the dimensions of aperture 322 may be equal to or somewhatlarger than the diameter of the radiation source 302. As indicated byarrow 50 in FIG. 5, optic device 308 with trapezoid shaped aperture 322may be placed on top of, and substantially surround, radiation source302. When an aperture such as aperture 322 is used, and when opticdevice 308 is placed on top of radiation source 302, FIG. 3 mayillustrate the radiation source 308 within aperture 322 of optic device308. As shown in FIGS. 3 and 5, the aperture in optic device 308 may beshaped to closely match the shape of the radiation source 302.Regardless of which aperture shaped is used, the radiation source 302may be fully immersed within the optic device 308 and may besubstantially surrounded by optic device 308, except for the side ofradiation source 302 that may rest on heat sink 304 or other supportingbase if a heat sink is not used, in an alternative embodiment.

The refractive index of optic device 308 may be in a range from about1.4 to about 1.7. Radiation source 302 may have a refractive index inthe range of about 1.7 to about 2.6. Referring to FIG. 4, there may beair spaces such as spaces 324, 326, and 328 between radiation source 302the inside of optic device 308. Referring to FIG. 4, there may also bean air space (not shown) between corner 330 of radiation source 302 andthe adjacent point of the optic device 308 inside aperture 320 andbetween corner 332 of radiation source 302 and the adjacent point of theoptic device 308 inside aperture 320. Referring to FIGS. 3 and 5, theremay also be air spaces between the sides of radiation source 302 and theinside of optic device 308 within aperture 322. There may also be airspaces between radiation source 302 and the inside of optic device 308within the aperture regardless of the respective shapes of the radiationsource and the aperture. In order to provide a transition for radiationpassing from radiation source 302 to optic device 308, a sealant may beplaced to fill the spaces between radiation source 302 and optic device308. Accordingly, a sealant may be placed in the spaces for any shape ofthe radiation source and any shape of the aperture within the opticdevice. The sealant may provide a transition for radiation passing fromthe respective radiation source to the optic device.

In an exemplary embodiment, the sealant may fill in each of the spacesas much as possible in order to obtain the best efficiency of radiationtransfer from the radiation source 302 to the optic device 308. Theefficiency of transferring radiation from radiation source 302 to opticdevice 308 may decrease if each of the spaces are not completely filled.The sealant may also be used as a binding material to bind the opticdevice 308 to the radiation source 302. A better bond between the opticdevice 308 and the radiation source 302 may result in better efficiencyof radiation transfer from radiation source 302 to optic device 308.

In an exemplary embodiment, the sealant material may be a silicon gel,epoxy, polymer or any other sealant that is substantially lighttransmissive, that has the necessary refractive index, and that ispliable enough to substantially seal the spaces. The sealant materialmay have a refractive index that is between the refractive index ofradiation source 302 and optic device 308. In an exemplary embodiment,the refractive index of the sealant may be in a range that is betweenthe refractive index of the radiation source 302 and the refractiveindex of optic device 308. For example, the refractive index of thesealant may be in the range of about 1.5 to about 2.3. In an exemplaryembodiment enough sealant should be used that may effect substantiallyfilling of all spaces including, but not limited to, spaces 320, 324 and326. Using a radiation source without a dome and using a sealant such asa gel as an interface between the radiation source and the optic devicemay allow the design of an optic device that is substantially shorterthan an optic device that uses a radiation source that is encapsulatedwith a dome. For example, referring to FIG. 2, the height 260 ofapparatus 200 may be about 20 mm. In contrast, referring to FIG. 3, theheight 360 of apparatus 300 may be about 3 mm. Using a sealant insteadof a dome therefore gives a user much more flexibility in the design andmanufacture of a light emitting apparatus that incorporates the featuresof SPE™ technique. For example, by using more or less sealant, a lightemitting apparatus may be manufactured that has a height in a range ofabout 2 mm to about 10 mm.

Referring back to FIG. 3, a lens 340 may be placed on top of, and over,the optic device 308 and the down conversion material 310. Lens 340 maybe used to focus light that may be forward transferred from the downconversion material 310 and light that may be reflected by the reflector306. Lens 340 may also have a refractive index that may compensate forthe refractive index of the air contained in space 342 that is formedwhen the lens 340 is placed on the optic device 308 and down conversionmaterial 310. Lens 340 may be a spherical lens or may be any other shapethat may direct the light as needed. Lens 340 may be attached to downconversion material using adhesive material. In an alternativeembodiment, lens 340 may also be attached to the heat sink 304. In yetanother alternative embodiment, lens 340 may be attached to both thedown conversion material 310 and the reflective cup 306.

FIGS. 6 to 9 illustrate alternative embodiments of the apparatus shownin FIGS. 3-5. In each of these embodiments, the optic device 308, downconversion material 310, radiation source 302 and aperture (not shown inFIGS. 6-9) may be the same as discussed with respect to any of FIGS.3-5. FIG. 6 illustrates the apparatus as having a thin film with amicro-lens array 342 on top of the optic device 308 and the downconversation material 310. In this embodiment, the lens array 342 may beattached to the down conversion material 310 alone, to the heat sink 304alone, or to both the down conversion material 310 and the heat sink304. FIG. 7 illustrates the apparatus without any lens on top of theoptic device 308 and the down conversion material 310. FIG. 8illustrates a lens 344 that may be attached only to the down conversionlayer 310. The lens 344 in this embodiment may be the any of the lensesillustrated and described in connection with FIGS. 3-5 and 7. FIG. 9illustrates a lens 346 that may be any of the lenses illustrated anddescribed in this application and a heat sink 348 with reflectivesurfaces 350 and 352. The reflective surfaces 350 and 352 of heat sink348 may not have a parabolic shape or an elliptical shape. Instead, oneor both of reflective surfaces 350 and 352 may have a linear shape.

FIG. 10 illustrates another embodiment of the invention. This embodimenthas a plurality of short wavelength radiation sources. FIG. 10illustrates an optic device 308 with a down conversion material 310 andan aperture 322 as illustrated in FIG. 5. These elements may have thesame sizes as the corresponding elements illustrated in FIG. 5. However,instead of a single short wavelength radiation source 302 as shown inFIG. 5, the embodiment illustrated in FIG. 10 may have three shortwavelength radiation sources 400, 402, 404 resting on heat sink 304.None of the short wavelength radiation sources 400, 402, 404 may beencapsulated by a dome. Because the size of aperture 322 in FIG. 10 maybe the same size as aperture 322 in FIG. 5, the sizes of one or more ofradiation sources 400, 402, 404 may be smaller than the size ofradiation source 302 shown in FIG. 5. In an exemplary embodiment, thesizes of one or more of radiation sources 400, 402, and 404 may be about0.3 mm by about 0.3 mm by about 0.3 mm. Although FIG. 10 shows threeradiation sources being placed on heat sink 304, it will be understoodthat two short wavelength radiation sources may be used; or more thanthree short wavelength radiation sources may be used as long as they fitwithin aperture 322. A sealant may be used between at least one of theradiation sources and the surface inside aperture 322. The sealant forthis embodiment of the invention and for all embodiments of theinvention disclosed in this application may be the same sealantdiscussed with respect to FIGS. 3-5.

FIG. 11 illustrates another embodiment of the invention having aplurality of short wavelength radiation sources. In FIG. 11, three shortwavelength radiation sources 302A, 302B, and 302C, each of which may bethe same size as short wavelength radiation source 302 that isillustrated in FIG. 5. None of the radiation sources 302A, 302B, and302C may be encapsulated by a dome. In order to accommodate these threeradiation sources, the optic device 408 having a down conversionmaterial 410 on portion 416 which may be an end of optic device 408 maybe a larger version of optic device 308 illustrated in FIGS. 3, 5, and10. In an exemplary embodiment, the size of aperture 422 illustrated inFIG. 11 may be about 6 mm. In addition, the size of heat sink 412 may bea larger version of heat sink 304 that is illustrated in FIGS. 3, 5, and10. In an exemplary embodiment, the length 470 of heat sink 412 may beabout 10 mm. Although FIG. 11 shows three short wavelength radiationsources 302A, 302B, 302C placed on heat sink 412, it will be understoodthat two short wavelength radiation sources may be used; or more thanthree short wavelength radiation sources may be used. If the number ofradiation sources is different than the embodiment illustrated in FIG.11, the size of aperture 422 and the size of heat sink 412 may bechanged to accommodate them. As with the other embodiments in thisapplication, a sealant may be used to seal all spaces (not shown)between each of the optic devices 302A, 302B, 302C and the surface ofoptic device 408 that is inside aperture 422.

FIG. 12 illustrates yet another embodiment of the invention having aplurality of short wavelength radiation sources. In FIG. 12, a singleheat sink 500 is shown having three separate heat sink sections 502,504, 506. Each of the heat sink sections may have its own respectivereflective surfaces forming reflective cups 508, 510, 512 and its ownrespective short wavelength radiation source identified as shortwavelength radiation sources 514, 516, and 520. In this embodiment,respective optic devices 522, 524, and 526 having respective downconversion materials 528, 530, 532 and respective apertures 534, 536,and 538 may be used. As with all of the other embodiments disclosed inthis application, none of the radiation sources 514, 516, or 520 mayhave a dome. Instead, a sealant may be used in the spaces (not shown)between each of the respective radiation sources and the respectiveinside surfaces of respective apertures 534, 536, 538 of optic devices522, 524, 526. Although FIG. 12 shows three radiation sources and othermatching elements, it will be understood that two radiation sources maybe used; or more than three radiation sources may be used. If the numberof radiation sources is different than is shown in the embodimentillustrated in FIG. 12, the number of optic devices may also bedifferent in order to match the number of radiation sources.

It will also be understood that for all embodiments illustrated in thisapplication, various configurations of lenses and various attachments ofsuch lenses may the same as illustrated and explained with respect tothe embodiments illustrated in FIGS. 6 to 9.

FIG. 14 illustrates an exemplary embodiment of a method that may be usedto manufacture any of the embodiments of the invention described inconnection with FIGS. 3-12. The method may be used to manufacture alight emitting apparatus that has a radiation source for emitting shortwavelength radiation, a down conversion material that receives at leastsome short wavelength radiation emitted by the radiation source, and anoptic device configured to extract radiation back transferred from thedown conversion material and/or radiation emitted from the shortwavelength radiation source. As shown in Block 700, the down conversionmaterial is placed on a first portion of the optic device. As explainedpreviously, the first portion of the optic device may be a first end ofthe optic device. As shown in Block 702, an aperture is formed in asecond portion of the optic device. The second portion of the opticdevice may be a second end of the optic device. It will be understoodthat the step of forming the aperture as shown in Block 702 may beperformed before the step of placing the down conversion material asshown in Block 700. Block 704 shows that a sealant is placed on asurface of the second portion of the optic device, where the surface isinside the aperture. After the sealant is placed on the inside surfaceof the aperture, Block 706 shows that the radiation source may be placedinto the aperture. When the radiation source is placed into theaperture, at least one surface of the radiation source may contact thesealant.

After the radiation source is placed into the aperture, at least firstand second spaces between the optic device and the radiation source maybe sealed, as shown in Blocks 708 and 710. After the spaces between theradiation source and the inside of the aperture have been sealed, theoptic device, with the radiation source inside the aperture, may beplaced on a support, as indicated in Block 712. The support may be aheat sink. It will be understood that the steps illustrated in Blocks708 and 710 may be performed after the step illustrated in Block 712.After spaces between the radiation source and the inside of the aperturehave been sealed and the device placed upon the support, a lens may beplaced adjacent the down conversion material, as indicated in Block 714.

FIG. 15 illustrates another method of manufacturing any of theembodiments of the invention described in connection with FIGS. 3-12. Inthis method, the steps shown in Blocks 800, 802, and 804 are the same asthe steps shown in Blocks 700, 702, and 704. After a sealant is placedon the inside surface of the aperture, the radiation source may beplaced on the support, which may be a heat sink, as shown in Block 806.It will be understood that the step of placing the radiation source on asupport as shown in Block 806 may be performed before the stepsillustrated in Blocks 800, 802, and 804. After the radiation source isplaced on the support, the optic device, with the sealant on its surfaceinside the aperture, is placed onto the support and over the radiationsource, as shown in Block 808. When this step is completed, the opticdevice may be substantially surrounding the radiation source, also asshown in Block 808. At this point, a plurality of spaces between theoptic device and the radiation source may be sealed, as shown in Block810. Then, a lens may be placed adjacent the down conversion material,as shown in Block 812. It will be understood that the step illustratedin Block 812 and the step illustrated in Block 714 may not be performed,for example, in manufacturing the embodiment shown in FIG. 7, where nosuch lens may be used.

FIG. 13 illustrates still another embodiment of the invention, wherein aplurality of reflective surfaces are adjacent the radiation source andthe optic device. A light emitting apparatus 600 is shown in FIG. 13.Light emitting apparatus 600 has an optic device 608 with a downconversion material 610 on a portion 616 of the optic device 608 thatmay be an end of optic device 608. Apparatus 600 may also have a shortwavelength radiation source 602 positioned on a heat sink 604. As is thecase with all of the other embodiments in this application, shortwavelength radiation source 602 may not be encapsulated by a dome. Heatsink 604 may form two reflective cups having reflective surfaces 612 and614. The first reflective cup and surface 612 may be adjacent the secondreflective cup and surface 614. The radius of reflective surface 612 maybe the same or different than the radius of reflective surface 614. Inaddition, reflective surface 612 may be comprised of a plurality ofsurfaces each of which may have a different radius. The number of radiicomprising reflective surface 612 may depend upon the height of opticdevice 608.

First reflective surface 612 may partially surround optic device 608 anddown conversion material 610. As discussed regarding other embodimentsof this invention, reflective surface 612 may direct light extractedfrom optic device 608 in the direction of down conversion material 610and in the direction of lens 640.

Radiation source 602 may be positioned at the bottom of heat sink 604 sothat the radiation source 602 may be partially surrounded by thereflective surface 614. First reflective surface 612 may be coupled tosecond reflective surface 614 at points illustrated by points 613, 615.A distance from the bottom 605 of heat sink 604 to points 613 and 615may be equal to or greater than the height of radiation source 602. Adiameter of end portion 618 of optic device 608 may be substantiallyequal to the distance between points 613 and 615.

In effect, radiation source 602 may be positioned in a well formed bythe bottom 605 of heat sink 604 and the reflective cup formed byreflective surface 614. Reflective surface may direct radiation emittedfrom the sides of radiation source 602 into optic device 608. Some ofthe radiation reflected by reflective surface 614 may be transmittedinto optic device 608 and may impinge on down conversion material 610.Some of the radiation reflected by reflective surface 614 may betransmitted into optic device 608 and may leave optic device 608 throughwalls 620, 622 without impinging upon down conversion material 610. Someof the radiation reflected by reflective surface 614 may be directedtoward lens 640 without impinging on down conversion material 610.

In this embodiment of the invention, optic device 608 does not have anaperture in its end 618. End 618 of optic device 608 may be placed on atop surface 603 of radiation source 602. A sealant (not shown) may beplaced in spaces 642, 644 between radiation source 602 and reflectivesurface 614 and in space 646 between radiation source 602 and end 618 ofoptic 608. The sealant may have the same characteristics and may be usedfor the same purposes as described in connection with other embodimentsof this invention.

A method of manufacture will now be described for manufacturing theapparatus illustrated in FIG. 13. FIG. 16 illustrates an exemplaryembodiment of the method that may be used to manufacture the embodimentof the invention described in connection with FIG. 13.

For this method of manufacturing a light emitting apparatus, there is aradiation source for emitting short wavelength radiation, a downconversion material that receives at least some short wavelengthradiation emitted by the radiation source, an optic device configured toextract radiation back transferred from the down conversion materialand/or radiation emitted from the short wavelength radiation source.There is also a first reflective cup and a second reflective cup. Thesecond reflective cup is adjacent the first reflective cup and forms awell.

As shown in Block 900, the down conversion material is placed on a firstportion of the optic device. As shown in Block 902, a first surface ofthe radiation source may be placed on a first surface of the well. Afterthis step is performed, the radiation source may be partially surroundedby the reflective cup forming the well. A first sealant may then beplaced between at least a second surface of the radiation source and asecond surface of the well, as shown in Block 904. A second sealant maythen be placed on a least a third surface of the radiation source, asshown in Block 906. The same kind of material, or different kinds ofmaterials, may be used for the first and second sealants. As shown inBlock 908, the optic device may then be placed within the firstreflective cup so that the optic device is partially surrounded by thefirst reflective cup and in contact with the second sealant. A lens maythen be placed adjacent the down conversion material, as shown in Block910.

Another embodiment of the invention is illustrated in FIGS. 17 and 18.FIG. 17 is a partial cross-section view of an alternative embodiment ofan optic device that may be mounted over a radiation source and onto areflector. FIG. 17 shows optic device 1008 and down conversion material1010 on an end 1016 of optic device 1008. FIG. 17 shows aperture 1020 inend 1018 of optic device 1008. Although aperture 1020 is illustrated ashaving a curved shape, aperture 1020 may have another shape that maymore closely approximate a shape of a radiation source. For example,aperture 1020 may have a trapezoidal shape. FIG. 17 also illustrates aradiation source 1032 mounted on a heat sink 1034 having a reflectivesurface 1036 forming a reflective cup. The dimensions andcharacteristics of the optic device 1008, the aperture 1020, the downconversion material 1010, the radiation source 1032, the heat sink 1034and the reflective surface 1036 may be the same as the dimensions andcharacteristics described in this application with respect to otherembodiments of the invention. Radiation source 1032 has a height 1033.The optic device may also be mounted over the radiation source 1032 andonto the heat sink in the same way as has been described with respect toother embodiments of the invention. FIG. 18 illustrates optic device1008 after it has been mounted over radiation source 1032 and onto heatsink 1034.

Referring to FIGS. 17 and 18, optic device 1008 may have side walls 1040and 1042 between end 1016 and end 1018. A first portion of the sidewalls 1040, 1042 may be substantially light transmissive and a secondportion of the side walls 1040, 1042 may not be substantially lighttransmissive. A reflective material 1046A may be applied to a portion ofwall 1040 and a reflective material 1046B may be applied to a portion ofwall 1042. Reflective materials 1046A and 1046B may be a highlyreflective paint. In an exemplary embodiment, the paint may be made ofbarium-sulfate-based paint and may exhibit about 97% reflectivity. In analternative embodiment, a vaporized aluminum coating, or a wavelengthselective coating may be used instead of paint.

As illustrated in FIG. 18, short wavelength radiation may be emitted notonly from the top 1050 of radiation source 1032, short wavelengthradiation may also be emitted from the sides 1052 and 1054 of radiationsource 1032. Arrows 1056 and 1058 indicate exemplary short wavelengthradiation rays being emitted from sides 1052 and 1054, respectively, ofshort wavelength radiation source 1032. It will be understood that shortwavelength radiation rays in addition to exemplary radiation rays 1056and 1058 may also be emitted from sides 1052 and 1054. In the absence ofreflective materials 1046A and 1046B, radiation rays from the sides 1052and 1054 may be extracted through walls 1040 and 1042 of optic device1008 and reflect off of reflective surfaces 1036. Some of the radiationreflected from reflective surfaces 1036 may be directed so that theyimpinge on down conversion material 1010. Other radiation reflected fromreflective surfaces 1036 may not be directed. Instead, for example, somereflected radiation may be directed toward and through spaces 1060 and1062 between down conversion material 1010 and reflective surfaces 1036.Any radiation that is reflected toward and through spaces 1060 and 1062will not be converted into white light by down conversion material 1010.

When reflective material 1046 is placed on the bottom portion of opticdevice 1008, radiation emitted from sides 1052 and 1054 of radiationsource 1032 may be directed toward, and impinge upon, down conversionmaterial by reflective material 1046. FIG. 18 shows exemplary radiationrays 1070 and 1072 that may be reflected by reflective materials 1046A,1046B when exemplary radiation rays 1056 and 1058 impinge on reflectivematerials 1046A, 1046B. It will be understood that short wavelengthradiation rays, in addition to exemplary reflected radiation rays 1070and 1072, may be emitted from sides 1052 and 1054 and may be reflectedby reflective materials 1046A, 1046B toward down conversion material1010.

It will be understood that a thickness of reflective materials 1046A,1046B has been exaggerated for purposes of illustration. In an exemplaryembodiment, the thickness of reflective materials 1046A, 1046B may bemuch thinner relative to the other elements illustrated in FIGS. 17 and18. In an exemplary embodiment, as illustrated in FIGS. 17 and 18,reflective materials 1046A, 1046B may be disposed along the outside ofwalls 1040 and 1042, respectively. In an alternative embodiment,reflective materials 1046A, 1046B may be embedded within walls 1040 and1042, respectively. In another alternative embodiment, reflectivematerials 1046A, 1046B may be disposed along an inside surface of walls1040 and 1042, respectively.

Referring to FIGS. 17 and 18, a length 1047 of reflective material1046A, 1046B may be up to 90% of the length of walls 1040 and 1042,respectively. As shown in FIG. 18, an exemplary embodiment of reflectivematerials 1046A, 1046B may extend from a point that is adjacent thebottom 1051 of radiation source 1032 to respective end points 1049A,1049B of reflective materials 1046A, 1046B that are beyond the top 1050of radiation source 1032 and below end 1016 of optic device 1008. In analternative embodiment, the length 1047 of reflective material 1046 mayresult in end points 1049A, 1049B of one or both of reflective materials1046A, 1046B being equal to, beyond, or under the height 1033 ofradiation source 1032 so that different amount of radiation emitted fromsides 1052 and 1054 hits the down conversion material 1010 depending onthe length 1047. That is, lengths of reflective materials 1046A and1046B may be the same or they may be different and the respectivelengths of reflective materials 1046A and 1046B may be symmetric or notsymmetric.

In this embodiment, the first portion of walls 1040, 1042 between endpoints 1049A, 1049B of reflective materials 1046A, 1046B and end 1016 ofoptic device 1008 may be substantially light transmissive. Because ofthe presence of reflective materials 1046A, 1046B, the second portion ofwalls 1040, 1042 between the bottom 1051 of radiation source 1032 andend points 1049A, 1049B may not be substantially light transmissive.Instead, the second portion of walls 1040, 1042 may be substantiallyreflective.

Another advantage of using reflective materials 1046A, 1046B may be areduction of a cost to manufacture an optic device such as optic device1008. If walls 1040, 1042 of optic device 1008 are substantially lighttransmissive over their entire length, the walls 1040, 1042 may have tobe highly polished along their entire length in order to use principlesof TIR. When reflective materials 1046A, 1046B are applied to the bottomportion of the optic device, the cost of manufacturing optic device maybe reduced because it may not be necessary to highly polish reflectivewalls 1040 and 1042 along their entire length. Instead, it may benecessary to highly polish only those portions of reflective walls 1040and 1042 that do have reflective material 1046A, 1046B. Referring toFIG. 18, when reflective materials 1046A, 1046B are disposed on or inreflective walls 1040 and 1042, it may be necessary to highly polishreflective walls 1040 and 1042 only from end points 1049A, 1049B ofreflective materials 1046A, 1046B to end 1016 of optic device 1008. Theremainder of walls 1040 and 1042 that coincide with length 1047 ofreflective materials 1046A, 1046B may have surfaces that are more roughthan the surfaces between end points 1049A, 1049B and end 1016 of opticdevice 1008. Reducing the amount of polishing that may be performed onoptic device 1008 may substantially reduce the cost of manufacturingoptic device 1008.

Still another embodiment of the invention is illustrated in FIGS. 19 and20. FIG. 19 is a partial cross-section view of this embodiment of theinvention. FIG. 20 is another partial cross-section view of thisembodiment illustrating an optic device being coupled to the otherelements of the embodiment. The embodiment illustrated in FIGS. 19 and20 is substantially the same as the embodiment that is illustrated inFIGS. 17 and 18.

The embodiment illustrated in FIGS. 19 and 20 may have an alternativeembodiment of a heat sink 1034. In FIGS. 19 and 20, an alternative formof an aperture 1022 is illustrated. As explained in an earlier part ofthis application, alternative shapes of the aperture may be used. Inthis embodiment, heat sink 1034 has a raised portion 1035. The height1085 of raised portion 1035 may be up to 50% of the height 1087 of heatsink 1034. Radiation source 1032 may be disposed on top of raisedportion 1035. FIG. 20 illustrates exemplary radiation rays 1056, 1058emitted from the sides of radiation source 1032 and being reflectedtoward down conversion material 1010 by reflective materials 1046A,1046B as exemplary reflected radiation rays 1070, 1072. As explainedpreviously, more or fewer radiation rays may be emitted from the sidesof radiation source 1032 and reflected toward down conversion material1010 by reflective materials 1046A, 1046B.

In the embodiment illustrated in FIG. 20, the aperture may cover theentire radiation source 1032 and substantially all of the raised portion1035 of heat sink 1034. In addition, sides 1080, 1082 of raised portion1035 may have reflective surfaces on them. The aperture may also coverreflective surfaces 1080, 1082. In other words, radiation source 1032may be fully immersed within the aperture and the raised portion 1035may be at least partially immersed in the aperture.

An advantage of the embodiment illustrated in FIG. 20 is that it mayreduce the amount of radiation that may be reflected back towardradiation source 1034 because there may be a greater volume of spacebetween the sides of radiation source 1034 and the reflective materials1046A, 1046B.

FIGS. 21 and 22 illustrate exemplary and alternative embodiments ofmethods that may be used to manufacture the embodiments illustrated inFIGS. 17-20. The method illustrated in FIG. 21 is the same method thathas been illustrated in FIG. 14 with the inclusion of an additional stepshown in Block 701. The step shown in Block 701 involves placingreflective material along, or embedded in, one or more walls of theoptic device. As illustrated, the step in Block 701 may be performedafter the step shown in Block 700 and before the step shown in Block702. However, it will be understood that the steps illustrated in Blocks700, 701, and 702 may be performed in any order.

The method illustrated in FIG. 22 is the same method that has beenillustrated in FIG. 15 with the inclusion of an additional step shown onBlock 801. The step shown in Block 801 involves placing reflectivematerial along, or embedded in, one or more walls of the optic device.As illustrated, the step in Block 801 may be performed after the stepshown in Block 800 and before the step shown in Block 802. However, itwill be understood that the steps illustrated in Blocks 800, 801, and802 may be performed in any order.

In all of the methods of manufacture described in this application, itwill be understood that the short wavelength radiation source used ineach of the various manufacturing processes does not have a dome. Inorder to obtain a short wavelength radiation source without a dome, auser may purchase it without the dome or may purchase it with a dome andthen remove the dome as an additional step in the manufacturing process.

Although the invention is illustrated and described herein withreference to specific embodiments, the invention is not intended to belimited to the details shown. Rather, various modifications may be madein the details within the scope and range of equivalents of the claimsand without departing from the invention.

What is claimed:
 1. A light emitting apparatus comprising: a first radiation source without a dome; a substantially transparent and light transmissive optic device devoid of scattering particles and phosphor, and comprising a planar top surface distal the first radiation source, a bottom surface proximal the first radiation source, and a transparent sidewall extending between the top surface and the bottom surface; a lens; a down conversion material comprising a flat layer including phosphor that is disposed on the planar top surface of the optic device between the lens and the radiation source; and a heat sink, upon which the radiation source is mounted, having a recess formed therein in which the radiation source, the optic device and the down conversion material are positioned, wherein an air space is defined between a boundary of the recess and the optic device.
 2. The light emitting apparatus of claim 1, further comprising a second radiation source having a dimension smaller than that of the first radiation source.
 3. The light emitting apparatus of claim 1, further comprising a sealant between the optic device and the first radiation source.
 4. The light emitting apparatus of claim 3, wherein the sealant has a refractive index of 1.5-2.3.
 5. The light emitting apparatus of claim 1, wherein the optic device has a refractive index of 1.4-1.7.
 6. The light emitting apparatus of claim 1, wherein the bottom surface has a width smaller than that of the top surface.
 7. The light emitting apparatus of claim 1, wherein the transparent sidewall comprises a straight portion, a curved portion, or both thereof. 